Solution P7.4.4
The following program plots the specified atmospheric $\mathrm{CO_2}$ concentration data over time on a graph.
import numpy as np
import matplotlib.pyplot as plt
dt = np.dtype([('date', 'f8'), ('co2_ppm', 'f8'), ('co2_ppm_trend', 'f8')])
data = np.loadtxt('co2_mm_mlo.txt', usecols=(2, 4, 5), dtype=dt)
fig = plt.figure()
ax = fig.add_subplot(111)
ax.plot(data['date'], data['co2_ppm'], label='Interpolated')
ax.plot(data['date'], data['co2_ppm_trend'], label='Trend')
ax.set_xlabel('Year')
ax.set_ylabel('$\mathrm{CO_2}$ concentration /ppm')
ax.legend(loc=0) # Legend in the "best" position
plt.show()
